It's too bad that U.S. Attorney Mary Beth Buchanan spoke injudiciously after she decided to dismiss charges against Cyril Wecht. He's known to criminal-TV junkies nationwide as a celebrity pathologist and Warren Commission critic.

He's known to Pittsburghers as a former county coroner, longtime Democratic Party muckety-muck and source of fabulously gassy quotes.

Had Ms. Buchanan not asserted her belief in Dr. Wecht's guilt, thus drawing the rebuke of his attorney, respected former governor and fellow Republican Dick Thornburgh, her situation would have made a wonderful test case for President Barack Obama's supposedly nonpolitical approach to the appointment of U.S. attorneys.

And the upshot might have been, finally, an honest discussion of the relationship between presidents and federal prosecutors -- setting straight the rampant misinformation and left-wing bleating of the past few years.

Ms. Buchanan already had drawn national attention for announcing that she would not resign immediately upon, and merely because of, the election of a new president. She's drawn increasing criticism locally for seeking to retry an entertaining old man whose brilliance is outstripped only by his buffoonish egotism.

But it's absurd to accuse Ms. Buchanan of politically motivated prosecution without considering that it's Dr. Wecht's defenders and apologists who may be motivated by partisanship -- now, and three decades ago.

The celebrity pathologist's first criminal trial for misusing public office for private gain ended with an acquittal -- in 1981. But a civil court upheld a surcharge from the county controller's office for exactly this problem. Dr. Wecht appealed, saw the amount increased, and finally settled with the county a decade later -- a decade later!

And he accuses Ms. Buchanan of shamelessness? Of being a sore loser? An onion has thicker skin than Cyril Wecht, and a more highly developed sense of irony, too.

Dr. Wecht faced similar charges in Ms. Buchanan's prosecution. The trial ended with a hung jury, and when a new judge excluded most of the government's evidence, she decided to drop the case.

In announcing her decision, she said, "If I could have a do-over, I'd still bring the case. Even with the tremendous criticism that's been dumped on this office, I still believe a crime was committed here." What she believes goes without saying -- and should not be said. Unless a crime is proven, what we've got is maybe sloppy bookkeeping.

But her words prompted Mr. Thornburgh to complain to the Justice Department last month, sparking a formal inquiry and almost certainly removing the possibility that she could continue to serve as U.S. attorney in the Obama administration. That's too bad, because otherwise, if those positions aren't supposed to have political overtones, why shouldn't she continue?

It was the injection of politics into the prosecutors' pure world, after all, that was the Democrats' objection to the Justice Department's 2006 firing of eight prosecutors, right? Baloney, of course. Although it's heartwarming to see Democrats worried about the careers of Republican-appointed Republicans, the truth is that politics has always played a role in this process -- and it will this time around, too.

Recent articles on the selection of U.S. attorneys have asserted that they "traditionally" tender their resignations when a new president is elected. On the contrary, recent decades provide a variety of approaches.

According to The New York Times, that state's federal prosecutors were allowed to finish their terms in the Ford-to-Carter and Carter-to-Reagan transitions -- a pattern likely followed in other states since it took Ronald Reagan two years, for instance, to fill a majority of these four-year positions.

Bill Clinton broke with that tradition by demanding the immediate resignation of the nation's 93 prosecutors, regardless of ongoing investigations, drawing widespread criticism from the law enforcement community. The Washington Post noted that George W. Bush took a more cautious, incremental approach and that Mr. Obama will do the same, having "learned from past mistakes."

The fact is, U.S. attorneys serve at the pleasure of the president and, while maintaining professional integrity, are supposed to further his goals. (That's why some of the 2006 firings had merit and some did not.)

Public corruption being a bipartisan failing, if local Democrats want a U.S. attorney to prosecute Republicans, they'll have to elect some. Ms. Buchanan has prosecuted what our region presented her, from corrupt officials to drug trafficking, possession of illegal firearms, sex slavery, child pornography and violent pornography depicting the torture and murder of women.

She can go, scolded at the end but satisfied with public service that has been, on the whole, vigorous and solid.